The growth technology

Organic nanofibers are grown in vacuum on muscovite mica by molecular beam epitaxy. The length of the nanofibers is controlled by adjusting the amount of deposited material and by controlling the temperature of the muscovite mica: increasing the temperature increases the length of the nanofibers. The temperature window where nanofiber growth occurs is about 50 K. The nanofibers can be grown from different molecules which eventually determine the physical properties such as luminescence color, electron mobility and hyperpolarizability, i.e. the ability to optically frequency double light.

Advantages

The technique is a bottom up technique, i.e. under the correct growth conditions the nanofibers multiply themselves by a very high factor (104 to 106), which makes the technique fairly easy to handle.
The technique is the same for the growth of nanofibers from different molecules.
The fact that nanofibers can be grown from a lot of different organic molecules gives the nanofibers applications in very different fields, for example security labeling, organic semiconductors, nanolasers, nanosensors, displays ….

Disadvantages

The molecules from which the nanofibers are made are quite expensive and in many cases need to be synthesized
The time it takes to fabricate a large array (10 to 100 cm2) of nanofibers with the current set up is rather long (30 – 60 minutes), which might be problematic for mass production.
The orientation of the nanofibers is determined by the orientation of surface dipoles in the freshly cleaved mica sheet. This means for all of the nanofibers to be pointing in the same direction, the mica sheet has to be cleaved in one piece. A technique for that has to be optimized.

Improvements

By synthesizing the molecules at the company the price can be drastically reduced. Since the nanofibers are small, the amount of material needed per nanofiber is extremely small.
The growth time can be reduced by using a more effective set up. The ultimate limit is the necessary slow deposition rate of 0.03 nm/s. For a film of effectively 50 nm mass thickness 5000/3 s are needed, i.e. roughly half an hour. However, per sample (about 17 cm2 at present) a large number (106 cm-2) of nanofibers are produced, which means that the time limit is given by the number of nanofibers needed for a given application as well as the maximum sample size.
The cleavage of mica onto a single sheet is possible, this is just a matter of technological improvements.